Committee Chair

Ranjan, Reetesh

Committee Member

Sreenivas, Kidambi; Margraves, Charles

Department

Dept. of Mechanical Engineering

College

College of Engineering and Computer Science

Publisher

University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)

Abstract

Turbulent premixed flames observed in energy conversion and propulsion applications are characterized by highly nonlinear, unsteady, and multi-scale processes. Previous numerical studies of freely propagating flames have utilized either forced or decaying background isotropic turbulence to provide detailed insights into the features of flame-turbulence interactions; however, none have made direct comparisons of cases where the turbulence decays or is sustained using a forcing strategy. This study compares the features of turbulent premixed flames via direct numerical simulations, where we consider both decaying and forced turbulence scenarios. Four turbulent premixed flames are simulated, corresponding to the thin reaction zone and broken/distributed reaction zone regimes. The comparative analysis focuses on the instantaneous reacting flow field, mean flame structure in both physical and state space, and the transport and dynamics of enstrophy. The results provide quantitative insights into how sustained versus decaying turbulence influences flame topology, small-scale vorticity generation, and reaction-zone structure.

Acknowledgments

I want to offer my sincere gratitude to my thesis advisor, Dr. Reetesh Ranjan, for his unwavering and invaluable guidance during this work. It has been both a privilege and an honor to work under his supervision, and the present study would not have been possible without his support. I would also like to extend my thanks to my thesis committee members, Dr. Kidambi Sreenivas and Dr. Charles Margraves, for their continued support during my graduate program at the University of Tennessee Chattanooga (UTC). Additionally, I want to thank Dr. Trevor Elliott for his support as well. I want to thank the members of the Fluids and Combustion Modeling Group for their assistance during this research work. I would like to acknowledge the grants from the National Science Foundation (Grant \#: 2301829) and the Center of Excellence in Applied Computational Science and Engineering at UTC for supporting this research work. I acknowledge the support of the staff at the UTC Research Institute for their assistance and access to the computational resources. Finally, I would like to thank Ms. A. James from the Department of Mechanical Engineering for her outstanding administrative support.

Degree

M. S.; A thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Master of Science.

Date

5-2026

Subject

Combustion--Mathematical models; Flame--Dynamics; Turbulence--Simulation methods

Keyword

Direct numerical simulation; linear forcing; turbulent premixed combustion; enstrophy analysis

Document Type

Masters theses

DCMI Type

Text

Extent

xiii, 83 leaves

Language

English

Rights

http://rightsstatements.org/vocab/InC/1.0/

License

http://creativecommons.org/licenses/by/4.0/

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